The present disclosure is related generally to the field of devices that exhibit diode behavior and, more particularly, to a geometric diode device, method and associated applications wherein the geometric diode is formed from an electrically conductive material.
The prior art contains numerous examples of devices that exhibit diode behavior in various applications. Most often, diodes are formed using semiconductor materials. As will be seen, Applicant recognizes herein that the use of semiconductor materials is problematic for a number of reasons.
In the prior art, most diodes are in a parallel-plate/sandwich geometry which results in a substantial capacitance between the plates. This capacitance results in a substantial RC time constant, which often limits the response time of the diode. Reducing the physical size of the device beneficially reduces the capacitance, however, the resistance of the device increases responsive to decreasing the size. These issues will be addressed further at one or more appropriate points below.
Applicant recognizes that a fundamental limit to the conversion efficiency of semiconductor photovoltaic cells results from the semiconductor bandgap of the semiconductor material, such that photons below the bandgap energy are thrown out or wasted and those with energy above the bandgap yield, at most, that bandgap's energy. Multi-junction cells improve upon this, but have their own limitations. Applicant further recognizes that, if one could instead rectify the radiant electromagnetic energy in the same way that power supplies rectify AC power, conversion efficiencies approaching 100% could be obtained, at least in principle. If such rectification could be accomplished using a low-cost, thin-film technology, this would represent a revolutionary advance in solar cell technology. Applicant is not aware, however, of any reports of photovoltaic rectifiers having conversion efficiencies that are believed to be practical. Moreover, it is believed that the primary obstacle, in this regard is the diode itself for various reasons which will be brought to light at appropriate points below.
A general concern with respect to semiconductor devices relates to manufacturing costs since there is a need for relatively complex manufacturing procedures, as will be discussed in more detail at one or more appropriate points hereinafter.
A recent approach using semiconductor material is seen in U.S. Pat. No. 7,224,026 by Song, et al (hereinafter, the Song Patent). The operation of the described devices appears to be premised upon modulation of the width of a channel through the formation of depletion layers.
Song himself notably takes a different approach in a number of papers in the literature including: “Nonlinear Electron Transport in an Asymmetric Microjunction: A Ballistic Rectifier” which was published on Apr. 27, 1998 in Physical Review Letters; “Electron Ratchet Effect in Semiconductor Devices and Artificial Materials with Broken Centrosymmetry” which was published on Apr. 22, 2002 and appeared in Applied Physics A; and “Room-Temperature Ballistic Nanodevices” which published in the Encyclopedia of Nanoscience and Nanotechnology in 2004 (hereinafter, referred to as the Song papers). The Song papers, however, continue to rely on the use of semiconductor materials, which can be unsuitable in the applications that are described below.
Another recent approach is taken in U.S. Pat. No. 6,563,185 (hereinafter, the '185 patent) wherein a metal-insulator-metal electron tunneling-based device is described. While the '185 patent provided sweeping advantages over the then-existing state-of-the-art by utilizing metal/insulator layered technology, Applicant submits that the present application provides still further advantages.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.